On 4/30/20 1:06 PM, Dmitry Osipenko wrote:
30.04.2020 01:00, Sowjanya Komatineni пишет:
+static int chan_capture_kthread_start(void *data)
+{
+ struct tegra_vi_channel *chan = data;
+ struct tegra_channel_buffer *buf;
+ int err = 0;
+
+ set_freezable();
+
+ while (1) {
+ try_to_freeze();
+
+ /*
+ * Source is not streaming if error is non-zero.
+ * So, do not dequeue buffers on error and let the thread sleep
+ * till kthread stop signal is received.
+ */
+ wait_event_interruptible(chan->start_wait,
+ kthread_should_stop() ||
+ (!list_empty(&chan->capture) &&
+ !err));
...
+static void tegra_channel_buffer_queue(struct vb2_buffer *vb)
+{
+ struct tegra_vi_channel *chan = vb2_get_drv_priv(vb->vb2_queue);
+ struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
+ struct tegra_channel_buffer *buf = to_tegra_channel_buffer(vbuf);
+
+ /* put buffer into the capture queue */
+ spin_lock(&chan->start_lock);
+ list_add_tail(&buf->queue, &chan->capture);
+ spin_unlock(&chan->start_lock);
+
+ /* wait up kthread for capture */
+ wake_up_interruptible(&chan->start_wait);
+}
The V4L doc says that buffers could be enqueued before streaming is
started. I guess it should be a trouble here, shouldn't it?
https://elixir.bootlin.com/linux/v5.7-rc3/source/include/media/videobuf2-core.h#L379
what trouble are you referring here?
I dont think so as we set min buffers needed as 2 always there will be 2
per-queued buffers.
But buffers from this queue will be dequeued only when ready to
processes in the capture thread
